Implantable neurostimulators are used to deliver therapy to patients to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, incontinence, sexual dysfunction, or gastroparesis. A neurostimulator delivers neurostimulation therapy via one or more leads that include electrodes located proximate to the spinal cord, pelvic nerves, or stomach, or within the brain of a patient. In general, the implantable neurostimulator delivers neurostimulation therapy in the form of electrical pulses.
Depending on the application for which they are implanted in a patient, neurostimulators may include a variety of electrical and mechanical components. Typically, a neurostimulator includes a rigid housing that houses all of its components, which are generally fragile, to protect the components from forces and fluids to which they would otherwise be exposed when implanted within the human body. The size and shape of a neurostimulator housing is dependent on the sizes and shapes of the components of the neurostimulator.
A neurostimulator is typically implanted within the abdomen, upper pectoral region, or subclavicular region of a patient. Leads or catheters are used to deliver therapy or monitor a physiological parameter at a remote location of the body. The leads or catheters extend from the neurostimulator housing for placement at a target site.
Implantation and positioning of leads and catheters can be difficult and time-consuming from the perspective of a surgeon, particularly where the neurostimulator is located a significant distance from the treatment or monitoring site. The increased surgical time, increased surgical trauma, and increased amount of implanted material associated with the use of leads and catheters can increase the risk to the patient of complications associated with the implantation of a neurostimulator.
In addition, selection of an efficacious target site for deployment of a lead or catheter is difficult. Some leads include an array of electrodes that can be selectively activated to target different nerve sites or create different energy fields. Once a lead is in place, however, repositioning of the lead is generally undesirable. In particular, the patient ordinarily must undergo an additional surgical procedure with associated risks. Accordingly, selection of a nerve site appropriate for therapeutic efficacy continues to be a concern.